1. Field of the Invention
The present invention relates to a relay apparatus and network relay method which transmit/receive data between different networks.
2. Description of the Related Art
An example of a standard for transmitting synchronous data such as video data or audio data that requires certain time axis synchronization on the transmitting and receiving sides is IEEE 1394 High Performance Serial Bus (to be referred to as a 1394 bus). The 1394 bus is mounted in a device as i.LINK, FireWire, or a DV terminal.
An example of a standard for relaying (bridging) 1394 buses is IEEE 1394.1. This bridge standard is merely used for relay of 1394 buses. Hence, in this bridge standard, two 1394 buses are independently handled. In relaying one 1394 bus to the other 1394 bus, a relay apparatus executes necessary processing such as processing for partner information or sending destination information and time axis correction for the 1394 buses. To be compatible with this bridge standard, compatibility from the physical level is required. Hence, in an LSI compatible to IEEE1394a-2000, since the partner is designated including a bus ID, and the bridge serving as a transmission destination of data communication cannot be recognized, data transmission/reception cannot be executed across a bus.
The above-described prior art has the following problem.
A conventional AV device incompatible to the bridge cannot communicate with another AV device that is present on another bus. Hence, a current LSI compatible to IEEE1394a-2000 must be changed. If IEEE 1394.1 is not used, two networks cannot be connected by any other standard.